One type of chip resistor having low resistance which is suitable for current detection uses a metal plate resistor body made of a Cu—Ni alloy or a Ni—Cr alloy to achieve low resistance in the order of mΩ.
In such a chip resistor, an adjustment is made to achieve target resistance by forming a trimming groove in a portion of the metal plate resistor body sandwiched between a pair of electrodes by means of laser machining using a laser trimming device. For such a chip resistor, there is a need to provide a higher precision of resistance at a demand for further advancement of products.
For example, there has been proposed a method for achieving the target resistance of the chip resistor by forming the trimming groove in the portion of the metal plate resistor body by means of punching instead of laser machining. However, since the position and shape of punching holes for formation of the trimming groove are determined depending on a sheet metal plate which is a collection of metal resistor plates, this method has a difficulty in performing the resistance adjustment with high accuracy based on the individual metal resistor plates. In addition, since there is a need for an additional dedicated device to form the punching holes, there are problems related to investment and device development in association with the necessity of a new production facility for introduction of the device.